This invention relates generally to video signal processing and more particularly to blending of images having different standardized color encoding.
As is known, video displaying and/or video recording equipment (xe2x80x9cvideo equipmentxe2x80x9d) receives a video signal, processes it, and displays it and/or records it. The video equipment, which may be a television, a personal computer, a work station, a video cassette recorder (VCR), a DVD player, a high definition television, a laser disc player, etc., receives the video signal from a video source. The type of video source varies depending on the type of video equipment. For example, the video source for a television may be a VCR, a DVD player, a laser disc player, an antenna operable to receive a broadcast television signal, a cable box, a satellite receiver, etc. The processing also varies depending on the type of video equipment. For example, when the video equipment is a computer, the processing may include scaling to fit the video images into a window, converting the video signal into RGB (red-green-blue) data, etc.
As is further known, encoding parameters (e.g., resolution, aspect ratio, color spaces, colorometries) of a video signal are standardized for the various types of video sources. For example, digital television video signals are standardized by the Advanced Television Standards Committee (ATSC), while regular television signals (e.g., VCR outputs, cable box outputs, broadcast television signals, etc.) are standardized by one of the National Television Standards Committee (NTSC) or the International Telecommunication Union (ITU), which prescribe Phase Alternate Line (PAL), or Sequential Couleur Avec Memoire (SECAM). Video signals displayed on a computer are standardized by de-facto evolving standards (e.g., VESA, or IEC) that prescribe the encoding parameters for analog RGB signals and digital RGB signals for CRT and flat panel displays.
Additional standards have been created to regulate the conversion of regular television signals into digital RGB data. For instance, Standard ITU-R BT601(xe2x80x9cThe 601 Standardxe2x80x9d) defines a single 3 by 3 matrix and corresponding coefficients for converting NTSC, PAL, and/or SECAM video data into digital RGB data. Standards have also been created for regulating conversion of digital television signals into digital RGB signals. For instance, a relevant portion of Standard SMPTE 274M, Standard SMPTE 240, and/or ITU-R BT.709 (xe2x80x9cthe 709 Standardxe2x80x9d) defines a matrix and coefficients for converting digital television to digital RGB data. In particular, the 709 standard defines two matrixes that are commonly used for converting MPEG (i.e., ISO/IEC 13818 specification) compliant digital television signals into digital RGB data. However, MPEG allows for six different matrixes to be used. Thus, video equipment designed to be digital television compliant would not be fully compliant with MPEG.
An issue arises due to the various standards, the various standard compliant video equipment, and the phase in of digital television -with full digital television occurring in the year 2006. During the phase in of digital television, regular TV will be used in a gradual phasing out manner. As such, some video equipment will be regular TV compliant, but not digital television compliant, newer video equipment may be digital television compliant, but not regular TV compliant, etc.
Therefore, a need exists for a method and apparatus that allow video equipment to readily convert video signals from one standardized color encoding to another.